.back-to-top {
    position: fixed;
    right: 24px;
    bottom: 24px;
    z-index: 900;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    border: none;
    border-radius: 50%;
    background: var(--color-gold-500);
    color: #fff;
    box-shadow: 0 8px 24px rgba(217, 119, 6, 0.35);
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(12px);
    transition: opacity 0.25s ease, transform 0.25s ease, visibility 0.25s ease, background 0.2s ease;
}
.back-to-top.is-visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}
.back-to-top:hover {
    background: var(--color-gold-600);
}
.back-to-top svg {
    width: 20px;
    height: 20px;
}

@media (max-width: 640px) {
    .back-to-top {
        right: 16px;
        bottom: 16px;
        width: 42px;
        height: 42px;
    }
    .back-to-top svg {
        width: 18px;
        height: 18px;
    }
}